My problem is that when I turn the shower water control to the hot side, the water coming out is warm at best. Sometimes, with no rhyme or reason, the water gets hot. I have to leave the water run to get warm as it comes out cold first. I have a Moen single knob (controls hot and cold) controller in my master shower stall. I have a gas water heater and it is located in my unfinished basement on the other side of a colonial style house. I need some advice to resolve this problem.